Suck-Chei Choi

Expression of protease-activated receptor 2 in ulcerative colitis

Although tryptase released from mast cells might play a key role in the pathogenesis of ulcerative colitis (UC), the role of protease-activated receptor 2 (PAR2), tryptase receptor, remains unclear in the pathogenesis of this disease. The expressions of PAR2 and tumor necrosis factor (TNF) &agr; in nine UC tissues and nine normal tissues were examined by immunohistochemistry. TNF-&agr; levels secreted from human leukemic mast cell line (HMC-1) after the treatment of PAR2 agonists were also measured by enzyme-linked immunosorbent assay. The PAR2 and TNF-&agr; proteins were more significantly detectable in UC tissues than in normal tissues. Furthermore, 65.2% of PAR2+ cells and 66.4% of TNF-&agr;+ cells in UC tissues were tryptase-positive cells. In other words, 60.6% and 46.3% of tryptase-positive cells in UC tissues were PAR2+ cells and TNF-&agr;+ cells, respectively. A &khgr;2 analysis showed correlation (p < 0.007) between PAR2 and TNF-&agr; in tryptase-positive mast cells. Moreover, PAR2 agonists significantly induced the TNF-&agr; secretion from HMC-1. These results indicate that the activation of the mast cells through PAR2 may be involved in the pathogenesis of UC.

Interleukin-27 polymorphisms are associated with inflammatory bowel diseases in a Korean population

Background and Aims:  The cytokine interleukin (IL)‐27 is composed of two subunits, Epstein–Barr virus‐induced gene 3 (EBI3) and p28, and IL‐27 is a novel IL‐12 family member that mediates between the innate and adaptive immune systems. We previously identified four polymorphisms in the human IL‐27 gene and we suggested that the polymorphism of IL‐27 is associated with the susceptibility to asthma. IL‐27 transcripts are significantly elevated in active Crohns disease (CD) but not in ulcerative colitis (UC). To determine whether these IL‐27 single nucleotide polymorphisms are associated with the susceptibility to inflammatory bowel disease (IBD), the genotype and allelic frequencies of the IL‐27 polymorphisms were analyzed between the IBD patients and the healthy controls.

Stress, coping, and depression in non-ulcer dyspepsia patients.

Thirty adults with upper gastrointestinal symptoms in the absence of structural organic disease diagnosed with non-ulcer dyspepsia (NUD) were compared to 30 healthy adults who had visited the hepatobiliary clinic for medical evaluation of non-organic complaints without NUD. Medical investigation in both groups were negative. Before independent gastrointestinal physicians conducted diagnostic evaluations, all subjects were evaluated for anxiety and depressive symptoms, stressful life events, coping style, and social support. The measures included Symptom Checklist 90-Revised (SCL-90-R), Beck Depression Inventory (BDI), Spielberger State-Trait Anxiety Inventory (STAI), Ways of Coping Checklist, and Interpersonal Support Evaluation List, and a self-report questionnaire, which measured the quantity of perceived stressful life events. The NUD patients reported significantly more symptoms of depression, more perceived stressful life events, less problem-focused coping, and less social support than the control subjects. Depressive symptoms were negatively correlated with interpersonal support, whereas, problem-focused coping was positively correlated with interpersonal support in the NUD patients. The two groups did not differ significantly in terms of anxiety and emotion-focused coping. The implications of these findings for the diagnosis and treatment of NUD are discussed.

Iron Chelator Triggers Inflammatory Signals in Human Intestinal Epithelial Cells: Involvement of p38 and Extracellular Signal-Regulated Kinase Signaling Pathways

Competition for cellular iron (Fe) is a vital component of the interaction between host and pathogen. Most bacteria have an obligate requirement for Fe to sustain infection, growth, and survival in host. To obtain iron required for growth, many bacteria secrete iron chelators (siderophores). This study was undertaken to test whether a bacterial siderophore, deferoxamine (DFO), could trigger inflammatory signals in human intestinal epithelial cells as a single stimulus. Incubation of human intestinal epithelial HT-29 cells with DFO increased the expression of IL-8 mRNA, as well as the release of IL-8 protein. The signal transduction study revealed that both p38 and extracellular signal-regulated kinase-1/2 were significantly activated in response to DFO. Accordingly, the selective inhibitors for both kinases, either alone or in combination, completely abolished DFO-induced IL-8 secretion, indicating an importance of mitogen-activated protein kinases pathway. These proinflammatory effects of DFO were, in large part, mediated by activation of Na+/H+ exchangers, because selective blockade of Na+/H+ exchangers prevented the DFO-induced IL-8 production. Interestingly, however, DFO neither induced NF-κB activation by itself nor affected IL-1β- or TNF-α-mediated NF-κB activation, suggesting a NF-κB-independent mechanism in DFO-induced IL-8 production. Global gene expression profiling revealed that DFO significantly up-regulates inflammation-related genes including proinflammatory genes, and that many of those genes are down-modulated by the selective mitogen-activated protein kinase inhibitors. Collectively, these results demonstrate that, in addition to bacterial products or cell wall components, direct chelation of host Fe by infected bacteria may also contribute to the evocation of host inflammatory responses.

Eupatilin Protects Gastric Epithelial Cells from Oxidative Damage and Down-Regulates Genes Responsible for the Cellular Oxidative Stress

PurposeThe formulated ethanol extract (DA-9601) of Artemisia asiatica has pronounced anti-inflammatory activities and exhibits cytoprotective effects against gastrointestinal damage. Here we investigated whether eupatilin, a major component of DA-9601, has a property of antioxidant activity and protects gastric epithelial cells from H2O2-induced damage.MethodsThe protective effect of eupatilin against H2O2-induced damages was studied in gastric epithelial AGS cells by measuring wound healing, cell proliferation, and cell viability. Global gene expression profiling was obtained by high-density microarray.ResultsHydrogen peroxide significantly delayed epithelial migration in wounded area. In contrast, eupatilin prevented the reduction of epithelial migration induced by H2O2. Eupatilin also ameliorated H2O2-induced actin disruption in AGS cells. Interestingly, treatment with eupatilin dramatically inhibited FeSO4-induced ROS production in a dose-dependent manner. In addition, eupatilin protected cells from FeSO4-induced F-actin disruption. With high-density microarray, we identified dozens of genes whose expressions were up-regulated in H2O2-treated cells. We found that eupatilin reduces the expression of such oxidative-responsible genes as HO-1, PLAUR and TNFRSF10A in H2O2-treated cells.ConclusionThese results suggest that eupatilin acts as a novel antioxidant and may play an important role in DA-9601-mediated effective repair of the gastric mucosa.

Involvement of p38 MAP kinase during iron chelator-mediated apoptotic cell death.

Iron is an essential element for the neoplastic cell growth, and iron chelators have been tested for their potential anti-proliferative and cytotoxic effects. To determine the mechanism of cell death induced by iron chelators, we explored the pathways of the three structurally related mitogen-activated protein (MAP) kinase subfamilies during apoptosis induced by iron chelators. We report that the chelator deferoxamine (DFO) strongly activates both p38 MAP kinase and extracellular signal-regulated kinase (ERK) at an early stage of incubation, but slightly activates c-Jun N-terminal kinase/stress-activated protein kinase (JNK/SAPK) at a late stage of incubation. Among three MAP kinase blockers used, however, the selective p38 MAP kinase inhibitor SB203580 could only protect HL-60 cells from chelator-induced cell death, indicating that p38 MAP kinase serves as a major mediator of apoptosis induced by iron chelator. DFO also caused release of cytochrome c from mitochondria and induced activation of caspase 3 and caspase 8. Interestingly, treatment of HL-60 cells with SB203580 greatly abolished cytochrome c release, and activation of caspase 3 and caspase 8. Collectively, the current study reveals that p38 MAP kinase plays an important role in iron chelator-mediated cell death of HL-60 cells by activating downstream apoptotic cascade that executes cell death pathway.

The aqueous extract of Solanum melongena inhibits PAR2 agonist-induced inflammation.

BACKGROUND Solanum melongena L. (Solanaceae) has antioxidant, analgesic, hypolipidemic and antiallergic activity. METHODS The anti-inflammatory effects of the water extract of the S. melongena (SMWE) were investigated in PAR2-mediated mouse paw edema. Paw edema was induced by injection of trypsin or trans-cinnamoyl-LIGRLO-NH(2) (tc-NH(2)) into the hindpaw of mice. The SMWE (1, 5, 10, and 100 mg/kg) was orally administered 1 h before induction of inflammation. RESULTS At doses of 5, 10, and 100 mg/kg, the SMWE showed significant inhibition of both paw edema and vascular permeability. The SMWE (10 mg/kg) significantly also inhibited PAR2 agonist-induced myeloperoxidase (MPO) activity and tumor necrosis factor (TNF)-alpha expression in paw tissue. CONCLUSION These results demonstrate that the SMWE inhibits PAR2 agonist-induced mouse paw edema.

Transcriptional regulation of IL‐8 by iron chelator in human epithelial cells is independent from NF‐κB but involves ERK1/2‐ and p38 kinase‐dependent activation of AP‐1

We have shown that the bacterial iron chelator, deferoxamine (DFO), triggers inflammatory signals including the production of CXC chemokine IL‐8, in human intestinal epithelial cells (IECs) by activating the ERK1/2 and p38 kinase pathways. In this study we investigated the mechanisms involved in IL‐8 generation by DFO, focusing on the transcription factors involved and the roles of both mitogen‐activated protein kinases (MAPKs) in the transcription factor activation. Treatment of human epithelial HT‐29 cells with DFO markedly up‐regulated the expression of the essential components of the transcription factor AP‐1 at a transcriptional level, while it minimally affected the expression of the NF‐κB subunits. DFO also induced AP‐1‐dependent transcriptional activity in HT‐29 cells, and this activity was further augmented by the wild‐type c‐Jun transfection. In contrast, the AP‐1 activity by DFO was markedly decreased by the dominant‐negative c‐Jun transfection. Electrophoretic mobility shift assays revealed that DFO increases the specific binding of AP‐1 but not of NF‐κB. Such AP‐1 binding and transcriptional activities were blocked by the inhibitors of the ERK1/2 and p38 kinase pathways, suggesting that both mitogen‐activated protein kinases (MAPKs) lie upstream of AP‐1. Besides its action on AP‐1, DFO also induced the specific binding of other transcription factors such as CREB and Egr‐1. In summary, our results indicate that iron chelator‐induced IL‐8 generation in IECs involves activation of ERK1/2 and p38 kinase and downstream activation of AP‐1. A possible link between iron status and two additional transcription factors, that is, CREB and Egr‐1, rather than NF‐κB, was also suggested. J. Cell. Biochem. 102: 1442–1457, 2007.

Eupatilin exhibits a novel anti-tumor activity through the induction of cell cycle arrest and differentiation of gastric carcinoma AGS cells.

In many cases, the process of cancer cell differentiation is associated with the programmed cell death. In the present study, interestingly, we found that eupatilin, one of the pharmacologically active ingredients of Artemisia asiatica that has been reported to induce apoptosis in human gastric cancer AGS cells, also triggers differentiation of these cells. Treatment of AGS cells with eupatilin induced cell cycle arrest at the G(1) phase with the concomitant induction of p21(cip1), a cell cycle inhibitor. This led us to test whether eupatilin may trigger AGS cells to differentiate into the matured phenotypes of epithelial cells and this phenomenon may be coupled to the apoptosis. Eupatilin induced changes of AGS cells to a more flattened morphology with increased cell size, granularity, and mitochondrial mass. It also markedly induced trefoil factor 1 (TFF1), a gene responsible for the gastrointestinal cell differentiation. Eupatilin dramatically induced redistribution of tight junction proteins such as occludin and ZO-1, and F-actin at the junctional region between cells. It also induced phosphorylation of extracellular signal-regulated kinase 2 and p38 kinase. Blockade of ERK signaling by PD098059 or the dominant-negative ERK2 significantly reduced eupatilin-induced TFF1 and p21 expression as well as ZO-1 redistribution, indicating that ERK cascades may mediate eupatilin-induced AGS cell differentiation. Collectively, our results suggest that eupatilin acts as a novel anti-tumor agent by inducing differentiation of gastrointestinal cancer cells rather than its direct role in inducing apoptotic cell death.

Increased expression of MIP-3α/CCL20 in peripheral blood mononuclear cells from patients with ulcerative colitis and its down-regulation by sulfasalazine and glucocorticoid treatment

Background: CCL20 expression is known to increase in the mucosal tissues of inflammatory bowel diseases (IBDs). Moreover, the discovery of Nod2 as the IBD1 susceptibility gene has underscored the significance of blood mononuclear cells in IBD pathogenesis. Methods: This study addresses whether CCL20 expression is similarly altered in peripheral blood mononuclear cells (PBMCs) of patients with ulcerative colitis (UC), a major type of IBD in Korea. Results: Expression of CCL20 was significantly up‐regulated in the PBMCs of patients with UC compared with those of normal healthy controls. Interestingly, untreated UC groups expressed higher levels of CCL20 mRNA than either treated UC or normal control groups, suggesting that CCL20 could be modulated by anti‐inflammatory drugs. Accordingly, a strong association between CCL20 levels and disease activity index was observed. Supporting these findings, results from a 3‐month follow‐up study revealed that the UC groups treated with 5‐aminosalicylic acid and glucocorticoid exhibited dramatic decreases of CCL20 mRNA in PBMCs, accompanied by ameliorated disease states. Moreover, tumor necrosis factor‐&agr;− or interleukin‐1&bgr;‐induced CCL20 secretion was greatly diminished by 5‐aminosalicylic acid and/or glucocorticoid treatment of human intestinal epithelial HT‐29 cells. Of note, CCR6+ cell populations were significantly reduced in the blood of severe patients with UC compared with normal controls, whereas no significant changes in CCR6+ cell populations were observed in the blood of patients with mild UC or acute colitis. Conclusions: Collectively, these findings suggest that CCL20 expression in blood mononuclear cells is associated with altered immune and inflammatory responses in patients with UC.